Abstract:

In South China, a disintegrated hill caused by serious soil erosion is called Benggang. On 8 positioned points, a total of 6 times field monitoring for soil moisture in Liantanggang, a Benggang in Wuhua County, Guangdong, was implemented by PR2/6 soil moisture sensor during the 3 consecutive years during 2011-2013. The distributional patterns, variations and influencing factors of Benggang soil moisture were analyzed in this paper. The 3-years monitoring data of the 8 monitoring points showed that the vertical changes of the Benggang soil moisture could be divided into three modes: gradual augmentation, equilibrium and fluctuation. The coefficient of variation of soil moisture in each layer decreased from the top to the bottom of the Benggang, that indicated that the moisture in the upper layers of soil changed obviously and in the lower layers were stable. Horizontally, the coefficient in each layer became smaller from the gully mouth to the headwall, that reflected that the soil moisture changed greatly in the lower part and changed slightly in the upper part. Overall, the top soil moisture was low. The soil layers of 100 and 200 mm in depth were the driest with the moisture below 20%. As the depth of the soil increased, the moisture increased. In the depths of 300 mm, 400 mm and 600 mm, the soil moisture was greater than 20%. The soil moisture in each layer increased gradually from Benggang gully outlet to the inside. Spatial distribution of the soil moisture was influenced by vegetation covers, soil properties, and local landforms, showing the spatial distribution pattern with stochastic changes. 7-days antecedent cumulative rainfall had a significant influence on soil moisture, which was the major factor that should be considered in the studies of the relationship among soil moisture and Benggang instability as well as slope runoff on talus surface.

Key words: Benggang, soil profile, moisture, spatial and temporal distribution, Liantanggang